South Australian scientist David Thompson has developed a system that uses anaerobic digestion technology to turn a range of plastics, including polyethylene, polypropylene, polystyrene and expanded polystyrene, into methane. His POET System process also produces environmentally safe, organic by-products that can be used as garden fertiliser and mulch.

Although initially developed for plastics, Thompson has tweaked the technology to process combined waste. He said this would be ideal for the fast food sector as its waste was often not able to be recycled because it was not made of the right material or it was contaminated with food waste.

“We’re exploring the potential of using the technology for a fast food chain where we can look at processing the food waste together with the plastic, paper and cardboard packaging all at once,” Thompson, the POET System CEO said.

“What we’ve been able to show through our in-house testing is that if we took a bin from a fast food outlet containing food scraps, paper, cardboard and plastics we would be able to process that all at once and create energy in the form of methane through the POET System.

“The key with the POET System is that we are able to convert the hydrocarbons within the plastic back to something that’s basically a carbon based inert, organic fertiliser.”

POET Systems was a 2017 semi-finalist in the Australian Technologies Competition, which assesses, mentors and promotes companies providing a uniquely Australian take on the future and is open to technologies that have global potential in a range of industries.

Thompson will file an application for patent protection this month and is looking for an investor to help build a demonstration plant capable of processing, initially, 5000 tonnes of plastic a year.

Picture: J MacPherson.

Thompson said in the fast food waste system, the rubbish collected from outlets would go to a central POET System in a regional area or city. He said his system would be ideally located alongside existing anaerobic digestion infrastructure such as what was commonly used at wastewater treatment plants or green waste processing.

“Knowing that I can put it through a particular process that the POET System already has without requiring any separation and then it all goes straight into the anaerobic digestor – that was the goose bump moment,” he said.

“I thought ‘if I can get this up and running’ how many of these fast food outlets are there?

“It would be nice to get a fast food chain to sponsor a program. You’ve also got the supermarkets with their out of date food that’s wrapped in plastic or on foam trays – all that can go through in one hit.”

The company, based in the South Australian capital Adelaide, is looking for an investment of about AU$2.5 million to help it build a 100-tonne a week plastics plant. Thompson said he was also interested in attracting investment from a fast food company to fast track a second system capable of digesting co-mingled waste.

“The nice thing about the POET system is that it’s a really soft system because although there are some mechanical processes at the beginning to make plastics attractive to the bacteria that digest it, it’s the bacteria that do all the work,” Thompson said.

“It’s a natural process and because we’re able to make plastics attractive to bacteria to colonise the waste and actually digest it that’s the beauty of the whole thing.”

The extension of China’s ‘Operation Green Fence’ policy came into effect in January, banning the importation of 24 categories of contaminated solid waste including paper, plastics, textiles and some metals. This caused prices for recyclable materials to crash and left waste management companies in the United States, Europe, Japan and Australia with vast amounts of unsaleable waste.

Before the ban, China imported almost 30 million tonnes of waste paper and 7 million tonnes of “recyclable” plastic a year – including about 30 per cent of Australia’s waste paper and plastic. This is on top of the estimated 1 million tonnes of contaminated plastic that is deemed unfit for recycling and sent to landfill in Australia each year.

A Senate Inquiry into the waste and recycling industry in Australia is due to report back on June 13. The issue is expected to be raised at a meeting of Australian state and federal environment ministers on April 27.

“What was recently deemed as being recyclable is no longer recyclable – there is no value in waste plastic because there is no viable waste processing capability in Australia and I’d like to think the POET system can meet a significant segment of that,” Thompson said.

“This opens up doors for us, we have an awful lot of plastic that is going to landfill in Australia and that’s being replicated all around the world.

“Once we get our demonstration plant built, order books from clients will open.”

Thompson said he has had the technology academically reviewed to prove that the science stacks up and the system is scalable.

“We’ve got conformity to international standards and nobody has ever done that,” he said.

“And I’ve been able to repeat that and take it to the next level to doing a single phase process that treats cardboard, plastic and food waste all through in one hit.

“We know what we need to do, we’re confident, we’ve done all the independent testing and all that can be put on the table with investors – real data, real results.”

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